JsonIgnore attribute is not inherited in overridden properties

[jmcginty]

Description

Marking a property in an abstract class as [JsonIgnore] does not get inherited when the property is overridden

Configuration

• Which version of .NET is the code running on? .net Core 3.1

Other information

Example test code to show the problem

using System;
using System.Text.Json;
using System.Text.Json.Serialization;
using Xunit;

namespace Test.TallyIt.JsonLibTest
{
    internal abstract class Animal
    {
        public int Id { get; set; }
        public string FirstName { get; set; }
        public DateTime Dob { get; set; }
        [JsonIgnore]
        public abstract bool IsIgnored { get; set; }
    }

    internal class Cat : Animal
    {
        public override bool IsIgnored { get; set; }
    }

    public class JsonTests
    {
        [Fact]
        public void TestSerialiseIntoCamelCase()
        {
            var cat = new Cat()
            {
                Id = 123782,
                Dob = new DateTime(2000, 7, 14),
                FirstName = "Fluffy",
                IsIgnored = true
            };

            var json = JsonSerializer.Serialize(cat);

            // This assert fails, I expected the JsonIgnore attribute to be derived
            Assert.Equal(@"{""id"":123782,""firstName"":""Fluffy"",""dob"":""2000-07-14T00:00:00""}", json);
        }
    }
}

[ghost]

Tagging subscribers to this area: @eiriktsarpalis, @layomia
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

Marking a property in an abstract class as [JsonIgnore] does not get inherited when the property is overridden

Configuration

• Which version of .NET is the code running on? .net Core 3.1

Other information

Example test code to show the problem

using System;
using System.Text.Json;
using System.Text.Json.Serialization;
using Xunit;

namespace Test.TallyIt.JsonLibTest
{
    internal abstract class Animal
    {
        public int Id { get; set; }
        public string FirstName { get; set; }
        public DateTime Dob { get; set; }
        [JsonIgnore]
        public abstract bool IsIgnored { get; set; }
    }

    internal class Cat : Animal
    {
        public override bool IsIgnored { get; set; }
    }

    public class JsonTests
    {
        [Fact]
        public void TestSerialiseIntoCamelCase()
        {
            var cat = new Cat()
            {
                Id = 123782,
                Dob = new DateTime(2000, 7, 14),
                FirstName = "Fluffy",
                IsIgnored = true
            };

            var json = JsonSerializer.Serialize(cat);

            // This assert fails, I expected the JsonIgnore attribute to be derived
            Assert.Equal(@"{""id"":123782,""firstName"":""Fluffy"",""dob"":""2000-07-14T00:00:00""}", json);
        }
    }
}

Author:	jmcginty
Assignees:	-
Labels:	area-System.Text.Json, untriaged
Milestone:	-

[eiriktsarpalis]

I can reproduce locally in .NET 5. Given that virtual properties already inherit attributes like JsonPropertyName it stands to reason that the same should be the case with JsonIgnore. @layomia thoughts?

[eiriktsarpalis]

Triage: assigning to future since not a regression and can be worked around by applying the same attribute in the derived classes.

[Maximys]

@layomia , I think this bug is linked with 51165. Can you get me possibility to fix they on my free time (I hope, on Saturday or Sunday of current week)?

[Jetski5822]

Just ran in to this - any idea when in 8.X this will be worked on?

[eiriktsarpalis]

.NET 8 has already shipped - we don't backport bugfixes to shipped versions of .NET unless they are regressions or security related bugs. In terms when this will get fixed in general, I can say with certainty that a fix is not in the cards for .NET 9.

[oddbear]

Not a solution, but it is possible to use customization as a workaround.
Something like:

void Main()
{
    var jsonSerializerOptions = new JsonSerializerOptions
    {
        TypeInfoResolver = new DefaultJsonTypeInfoResolver
        {
            Modifiers = { InheritJsonIgnore }
        }
    };

    var cat = new Cat()
    {
        Id = 123782,
        Dob = new DateTime(2000, 7, 14),
        FirstName = "Fluffy",
        IsIgnored = true
    };

    var json = JsonSerializer.Serialize(cat, jsonSerializerOptions);
    json.Dump(); // {"Id":123782,"FirstName":"Fluffy","Dob":"2000-07-14T00:00:00"}
}

// Modified example from: https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json/custom-contracts
static void InheritJsonIgnore(JsonTypeInfo jsonTypeInfo)
{
    if (jsonTypeInfo.Kind is not JsonTypeInfoKind.Object)
        return;
    
    for (int i = 0; i < jsonTypeInfo.Properties.Count; i++)
    {
        if (jsonTypeInfo.Properties[i].AttributeProvider is not PropertyInfo propertyInfo)
            continue;

        if (propertyInfo.GetCustomAttribute<JsonIgnoreAttribute>() is null)
            continue;

        jsonTypeInfo.Properties.RemoveAt(i--);
    }
}

internal abstract class Animal
{
    public int Id { get; set; }
    public string FirstName { get; set; }
    public DateTime Dob { get; set; }
    [JsonIgnore]
    public abstract bool IsIgnored { get; set; }
}

internal class Cat : Animal
{
    public override bool IsIgnored { get; set; }
}

[rmannibucau]

Same there, the API is flagged as inherited but the impl is not which is bothering cause it means you can leak a parent state whereas the child doesn't always have to care about it so hope .NET 9 gets it fixed since it doesn't look crazy as fix.